[Feature request] Foveated Rendering

[emile0909]

When I was reading OpenXR 1.1 specification, I see XR_VIEW_CONFIGURATION_TYPE_PRIMARY_STEREO_WITH_FOVEATED_INSET in section 8.1. Primary View Configurations. The example in the doc shows that if we render the inset (possibly central) small view with high resolution and outer view with low resolution, we can reduce like 75% of the pixels.

I was very excited that my poor 4060 Ti can behave like 4090, as UEVR performance is dominated (in my opinion) by number of pixels when we have high resolution scale.

I tried Quad-Views-Foveated with the game Pavlov VR. I increased the resolution scale both in SteamVR and game setting. The feature works as expected. The game render time drops dramatically.

I looked at UEVR code, OpenXR side change seems doable, the views size would be changed from 2 to 4. But the UE engine and hook code looks too complex for me. I don't even find where the left/right eye 2 view's pose/projection data are set for the rendering.

If we don't require 4090 to play most UE games, if we just need the recommended hardware on Steam store page to play the game, that would be awesome.

Is this feature doable in UEVR? And worth doing?

[praydog]

It's been tested. Quad views hurts performance in this because most games don't have instanced stereo enabled.